We're now in the peak of summer and for the next few weeks we can expect warm nights, hot days and high humidity at times.

High humidity in New Zealand is normal, in winter it causes foggy damp mornings but in summer when it's combined with heat it leads to muggy conditions.

On Tuesday humidity levels were at 99 per cent for some, which basically means if you sweat the air is so saturated around you it cannot absorb it - so your skin remains sticky and gross and you can't cool down, says WeatherWatch.co.nz

"Today - despite the heat - the humidity levels have eased for some, but with recent rain inland some places will feel hot and humid (and you can add a few more degrees to your daytime high to reflect the 'feels like' temperature when it's hot and humid).

"As we head into the end of this weekend the airflow around New Zealand will begin to tilt more north east again and that's because next week a sub-tropical low is expected to drop south over the country bringing heavy rain, strong winds, and large seas (in fact it may coincide with our next king tide so more coastal flooding is possible in northern facing areas)."

This sub-tropical low next week is likely to bring extreme humidity to some regions and high rainfall rates, says the weather organisation.

Before it arrives the northerlies will boost temperatures even further into the low to mid 30s in both islands with isolated thunderstorms too.

Southland - once again you're expected to reach the low 30s C next Monday and Tuesday ahead of this northern low (and a cooler change around next Wednesday).

WeatherWatch.co.nz is now forecasting daytime highs in Central Otago at the start of next week may now reach the mid to late 30s in some pockets.

"The North Island's eastern areas and interior regions will also push into the low 30s with higher humidity than inland parts of the South Island.

"The next week across New Zealand will be hot and at times humid and muggy. Summer heat usually peaks from late January to mid February in New Zealand."